tri: A triangulation object

Description

R object that represents the triangulation of a set of 2D points,
generated by tri.mesh or add.constraint.

Arguments

n

Number of nodes

x

x coordinates of the triangulation nodes

y

y coordinates of the triangulation nodes

tlist

Set of nodal indexes which, along with tlptr,
tlend, and tlnew, define the triangulation as a
set of n adjacency lists – counterclockwise-ordered sequences of
neighboring nodes such that the first and last neighbors of a
boundary node are boundary nodes (the first neighbor of an interior
node is arbitrary). In order to distinguish between
interior and boundary nodes, the last neighbor of each boundary node
is represented by the negative of its index.

tlptr

Set of pointers in one-to-one
correspondence with the elements of tlist.
tlist[tlptr[i]] indexes the node which follows
tlist[i] in cyclical counterclockwise order
(the first neighbor follows the last neighbor).

tlend

Set of pointers to adjacency lists. tlend[k]
points to the last neighbor of node k for
k = 1,...,n. Thus, tlist[tlend[k]]<0 if and
only if k is a boundary node.

tlnew

Pointer to the first empty location in tlist
and tlptr (list length plus one).

nc

number of constraints

lc

starting indices of constraints in x and y

call

call, which generated this object

Note

The elements tlist, tlptr, tlend and tlnew
are mainly intended for internal use in the appropriate Fortran
routines.